Diffusion-weighted and Dynamic Contrast-enhanced MRI of Metastatic Bone Tumors: Correlation of the Apparent Diffusion Coefficient, K(trans) and ve values

PURPOSE: To investigate whether quantitative parameters derived from Diffusion-weighted magnetic resonance imaging (DW-MRI) correlate with those of Dynamic contrast-enhanced MRI (DCE-MRI). MATERIALS AND METHODS: Thirteen patients with pathologically or clinically proven bony metastasis who had undergone MRI prior to treatment were included. The voxel size was 1.367 x 1.367 x 5 mm. A dominant tumor was selected and the apparent diffusion coefficient (ADC) value and DCE-MRI parameters were obtained by matching voxels. DCE-MRI data were analyzed yielding estimates of K(trans) (volume transfer constant) and ve. (extravascular extracellular volume fraction). Statistical analysis of ADC, K(trans), and ve value was conducted using Pearson correlation analyses. RESULTS: Fifteen lesions in pelvic bones were evaluated. Of these, 11 showed a statistically significant correlation (P < 0.05) between ADC and K(trans). The ADC and K(trans) were inversely related in 7 lesions and positively related in 4 lesions. This did not depend on the primary cancer or site of metastasis. The ADC and ve of 9 lesions correlated significantly. Of these, 4 lesions were inversely related and 5 lesions were positively related. CONCLUSION: Unlike our theoretic hypothesis, there was no consistent correlation between ADC values and K(trans) or between ADC values and ve in metastatic bone tumors.

Diffusion-Weighted Magnetic Resonance Imaging for the Evaluation of Prostate Cancer: Optimal B Value at 3T

OBJECTIVE: To retrospectively determine the optimal b value of diffusion-weighted imaging (DWI) for predicting the presence of localized prostate cancer, and to evaluate the utility of DWI under different b values in differentiating between cancers and benign prostatic tissues. MATERIALS AND METHODS: Eighty patients with suspected prostate cancer underwent MRI including DWI at 3T, followed by radical prostatectomy. DWI was examined under different b values. Apparent diffusion coefficient (ADC) maps were generated by using b = 0, and other b values of 300, 700, 1000 or 2000 s/mm2. For predicting the presence of cancers, four different ADC maps were analyzed independently by two blinded readers. ADCs were measured in benign and malignant tissues. RESULTS: For predicting the presence of 110 prostate cancers, the sensitivity and area under the curve (AUC) for an experienced reader was significantly greater at b = 1000 (85% and 0.91) than b = 300, 700 or 2000 s/mm2 (p < 0.01). For a less-experienced reader, the AUC was significantly greater at b = 700, 1000 or 2000 than b = 300 s/mm2 (p < 0.01). Mean ADCs of the cancers in sequence from b = 300 to 2000 s/mm2 were 1.33, 1.03, 0.88 and 0.68 x 10(-3) mm2/s, which were significantly lower than those of benign tissues (p < 0.001). CONCLUSION: The optimal b value for 3T DWI for predicting the presence of prostate cancer may be 1000 s/mm2.

Digital Tomosynthesis for PNS Evaluation: Comparisons of Patient Exposure and Image Quality with Plain Radiography

OBJECTIVE: We investigated low dose digital tomosynthesis (DT) for the evaluation of the paranasal sinus (PNS), and compared its diagnostic accuracy with a PNS radiography series (XR). MATERIALS AND METHODS: We enrolled 43 patients for whom XR, PNS DT, and OMU CT were performed. We measured effective doses (EDs) of XR, DT, and OMU CT using Monte Carlo simulation software. Two radiologists performed independent observation of both XR and DT. For seven PNSs, they scored anatomic conspicuity of sinuses and confidence on the presence of sinusitis using nine point scales. OMU CT was observed by the third radiologist and the findings were regarded as reference standard. We compared scores for conspicuity and sinusitis confidence between XR and DT. RESULTS: Mean EDs were 29 +/- 6 microSv, 48 +/- 10 microSv, and 980 +/- 250 microSv, respectively, for XR, DT, and CT. Mean scores for conspicuity were 6.3 and 7.4, respectively, for XR and DT. Sensitivity per patient basis for sinusitis detection were 52% and 96%, respectively, for XR and DT in observer 1 (p = 0.001) and 80% and 92% for observer 2 (p = 0.25). Specificities for sinusitis exclusion were 100% for both XR and DT for observer 1 and 89% and 100% for observer 2 (p = 0.50). Accuracies for sinusitis diagnosis were 72% and 98%, respectively, for XR and DT for observer 1 (p = 0.001) and 84% and 95% for observer 2 (p = 0.125). CONCLUSION: Patient radiation dose from low dose DT is comparable with that of PNS XR. Diagnostic sensitivity of DT for sinusitis was superior to PNS XR.

Gadoxetic Acid (Gd-EOB-DTPA)-Enhanced MRI versus Gadobenate Dimeglumine (Gd-BOPTA)-Enhanced MRI for Preoperatively Detecting Hepatocellular Carcinoma: an Initial Experience

OBJECTIVE: This study was designed to compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine-enhanced MRI for preoperatively detecting hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Eighteen consecutive patients (17 men and one woman, age range: 31-73 years) with 22 HCCs underwent examinations with gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI on a 3.0-Tesla unit. The diagnosis of HCC was established after surgical resection and pathological conformation. Three observers independently reviewed each MR image in a random order on a tumor-by-tumor basis. The diagnostic accuracy of these techniques for the detection of HCC was assessed by performing an alternative free-response receiver operating characteristic (ROC) analysis. The sensitivity and positive predictive values were evaluated. RESULTS: The average value of the area under the ROC curve (Az) for gadoxetic acid enhanced MRI (0.887) was not significantly different from the Az (0.899) for gadobenate dimeglumine-enhanced MRI (p > 0.05). The overall sensitivities of gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI were 80% and 83%, respectively, with no significant difference (p > 0.05). The differences of the positive predictive values for the two contrast agents for each observer were not statistically significant (p > 0.05). CONCLUSION: The diagnostic performance of gadoxetic acid-enhanced MRI and gadobenate dimeglumine-enhanced MRI for preoperatively detecting HCC is quite similar.